After some Googling, I’ve at least discovered that I’m allowed to have RAID 0 arrays with persistent superblocks.

From that page:

– RAID0 and linear now fully supports persistent superblocks ========================================
the bugs reported by Stephen Tweedie got fixed, and full support for persistent superblocks has been added. A RAID0 array from now on refuses to run if a device is missing or a numbering irregularity gets detected.